NSDate，比较两个日期 [英] NSDate, comparing two dates

问题描述

好的，我已经在这几天工作了，而且我被卡住了。我想要做的是将当前时间与预定时间进行比较。我想要发生的是，每天在特定时间我想要触发某些代码，但不是在我指定的时间之前。

Ok, I have been working on this for a couple of days now and am stuck. What I am trying to do is compare the current time with a predetermined time. What I want to happen is, Everyday at certain times I want certain code to fire, but not before the time of day that I specify.

所以，基本上如果当前时间等于或等于预定时间然后触发此代码。或者触发这行代码。

so, basically if the "current time" is the same or equal to "predetermined time" then fire this code. Or fire this line of code.

听起来很简单，但是我在抓两次比较时遇到了麻烦。

Sounds simple, but I am having trouble grabbing comparing the two times.

我已将字符串格式化为类似日期

I have formatted a string to a date like so

     NSString* dateString = @"11:05 PM";
        NSDateFormatter* firstDateFormatter = [[[NSDateFormatter alloc] init] autorelease];
        [firstDateFormatter setDateFormat:@"h:mm a"];
        [firstDateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
        NSDate* date = [firstDateFormatter dateFromString:dateString];
        NSLog(@"date %@",date);

然后我就这样抓住当前时间

then i grab the current time like so

   NSDate *currentTime = [NSDate dateWithTimeIntervalSinceNow:[[NSTimeZone localTimeZone]     secondsFromGMT]];
NSDateComponents* comps = [[NSCalendar currentCalendar] 
                           components: NSHourCalendarUnit |NSMinuteCalendarUnit 
                                |NSSecondCalendarUnit fromDate:currentTime];
 [[NSCalendar currentCalendar] dateFromComponents:comps];

那我该怎么比较这两次呢？我已经尝试了我能想到的一切，请帮助。

SO how do I compare these two times? I have tried everything I can think of, please help.

推荐答案

你可以尝试以下代码行吗？

Can you try below lines of code?

switch ([dateOne compare:dateTwo]){
     case NSOrderedAscending:
          NSLog(@"NSOrderedAscending");
    break;
    case NSOrderedSame:
          NSLog(@"NSOrderedSame");
    break;
    case NSOrderedDescending:
         NSLog(@"NSOrderedDescending");
    break;
}

但在您的情况下，我认为您需要将两个日期保持为相同的格式。 。或者像这样的东西

But in your case I think you need to keep both dates in same format ..or some thing like this

 NSDateComponents *components = [[NSCalendar currentCalendar] components:NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:[NSDate date]];
    [components setHour:23];//change your time to 24hrs formate 
    [components setMinute:05];
    [components setSecond:00];


    NSDate *dateOne = [[NSCalendar currentCalendar] dateFromComponents:components];

    components = [[NSCalendar currentCalendar] components:NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:[NSDate date]];

     NSDate *dateTwo = [[NSCalendar currentCalendar] dateFromComponents:components];

并在dateOne和dateTwo之间进行比较。

and do comparison between dateOne and dateTwo.

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